I'm just going to contectualise this by saying I l...

I'm just going to contectualise this by saying I love the medieval history of London so I'm probably a little biased, but the whole Tower of London experience was awesome!
We went on a beautiful sunny afternoon and managed to sneak in just as one of the Beef Eaters (the guide/guard) named Spike was starting the tour. The guided tour lasted about 30 mins and went into the history both the buildings themselves and the happenings within the buildings during the first half of the second century. Spike was a fantastic speaker and we learnt a lot!
After that we spent a good few hours having a look at all the other parts of the tower; the Crown Jewels and history of the monarchy, armory (weapons and armor from the year 1000 to now), the history of the soldiers themselves during the multiple wars fought in and by London (again between 1000-now) and simply taking in the views and reveling in the knowledge that everything around us was pretty much the same as it was 1000 years ago.
It's a little pricey as far as tours go but I'd highly recommend putting aside a few hours and seeing it!